1. Technical Field
The present invention relates to structural inserts adapted for use with hollow structural members, and more particularly, to a localized or global insert comprising at least one active material operable to reversibly change, upon activation or deactivation, the insertability, or a characteristic, such as stiffness, damping, geometric configuration, or the energy absorption rate of the resultant assembly.
2. Background Art
Structural inserts, such as metal plates, “I” beams 1 (prior art, FIG. 1a), “L” and “C” shaped angle irons 2,3 (FIGS. 1b,c), lattices, truces, and foam materials have been developed to provide reinforcement to hollow members 4. To effect their intended function, these inserts are often press-fitted (when engaging opposite interior surfaces), drawn, or hydroformed into place, and then joined together, typically through spot or seam welding. The lack of access to the interior of the member or its surrounding space once incorporated into a product (e.g., a vehicle), often results in an inability to retrofit the product in this manner. Alternatively, the insert may be secured in place prior to forming the hollow structural member. Once in place, the member and insert assembly cooperate to present a one-size-fits-all structural solution, wherein the resultant assembly characteristics, such as structural capacity, flexure modulus, and damping/energy absorption rate, remain constant. As a result, conventional inserts continue to present concerns in the art, including, but not limited to, the requirement of extensive labor and construction costs, as well as the inability to change or tune structural characteristics for a given condition and/or impending event. Moreover, conventional methods of placing inserts also present concerns, where attempting to retrofit an existing product.